Credit

Caption

Light micrograph of a read-write magnetic ferrite head from a 3.5-inch floppy disk drive. Particles and abrasions are visible on the surface of the head. The head is an electromagnet. To write data a current is applied to the head, creating a magnetic field. The polarity of the magnetic field, which depends upon the direction of the current, corresponds to the ones and zeros of binary code. This system is sensitive to dirt-induced errors. To read the data a magnetic field is applied to the head. The magnetic particles in the disk induce a tiny voltage in the magnetic head, which is converted to binary data. The maximum transfer rate of 3.5-inch floppy disk, is around 1,000 kilobits per second. Field of view size: 0.43 x 0.64 millimetres.